Variable denier yarn

ABSTRACT

TEXTILE ARTICLES COMPRISE YARNS OF A SYNTHETIC THERMOPLASTIC MATERIAL, EXPECIALLY POLYETHYLENE TEREPHTHALATE, IN WHICH THE INDIVIDUAL FILAMENTS COMPRISE ZONES OF AT LEAST THREE DIFFERENT THICKNESS, THE THICKEST HAVING THE LOWEST CRYSTALLINITY AND ORIENTATION AND VICE VERSA; THE FILAMENTS ALSO HAVE A NONSPIRAL THREE-DIMENSIONAL CRIMP, AND THEY, AND THE YARNS COMPRISING THEM HAVE HIGH APPARENT VOLUME. THE YARN IS MADE BY ONLY PARTIALLY STRETCHING THE INITIAL YARN IN AT LEAST TWO STAGES, DURING AT LEAST ONE OF WHICH THE YARN IS IN CONTACT WITH A CRACK OR FILLURE PROMOTING AGENT, AND SUBSQUENTLY GIVING THE YARN, BEFORE OR AFTER IT IS MADE UP, A HEAT TREATMENT WHILE IT IS IN A RELAXED STATE.

United States Patent [72] inventor Michel Buzano Villeurbanne Rhone, France [2]] Appl. No. 799,796

[22] Filed Feb. 17, 1969 [45] Patented June 28, 1971 [32] Priority Feb. 19, 1968 [33] France [73] Assignee Societe Rhodiaceta. Paris. France [54] VARIABLE DENIER YARN 7 Claims, 2 Drawing Figs.

52 us. Cl 57/140, 161/179, 161/180, 264/167, 264/168 [51] lnt.Cl D02g l/00, D02g 3/00 [50] Field of Search ..57/l40, 140

Primary Examiner-John Petrakes Attorney-Cushman, Darby and Cushman ABSTRACT: Textile articles comprise yarns of a synthetic thennoplastic material, especially polyethylene terephthalate, in which the individual filaments comprise zones of at least three different thicknesses, the thickest having the lowest crystallinity and orientation and vice versa; the filaments also have a nonspiral three-dimensional crimp, and they, and the yarns comprising them, have a high apparent volume. The yarn is made by only partially stretching the initial yarn in at least two stages, during at least one of which the yarn is in contact with a crack or fillure promoting agent, and subsequently giving the yarn, before or after it is made up, a heat treatment while it is in a relaxed state.

PATE-N'TEU JUN28 I971 FIG. 7.

, l vArti'AaLE DENIER YARN This invention relates to new textile articles comprising textured yarns of high apparent volume having a three-dimensional nonspiral crimp, and a high dimensional stability and to a process and a devicefor the manufacture of such yarns.

A large variety of so-called textured yarns already exists, and these can be schematically classified into spirally crimped yarns and nonspirally crimped yarns. The former are obtained by twisting, setting and untwisting, generally by means of a continuous false twist process. These yarns are noteworthy for a high elasticity which must for certain applications be reduced by means of a supplementary setting treatment.

The nonspirally crimped yarns have crimps of various configurations and are generally much less elastic, which is usually not undesirable. They are obtained by various processes using mechanical, pneumatic or mechanical-pneumatic devices. These processes suffer from the disadvantage of a relatively limited production speed as a result of the fact that moving elements are used.

Chemical processes have also been used to texture yarns. In fact it appears logical a priori to hope to obtain reproducible conditions more easily by chemical means.

However this method of texturizing has hitherto remained little developed because the processes which have been discovered have not given industrial results comparable to those obtained by mechanical means such as for example by false twist.

It was observed a long time ago that polyamide yarns can be cold-drawn more easily when moistened with water or with a hydroxylic nonsolvent such as lower aliphatic alcohol, a glycol or a hydroxy-ester.

it has been proposed to manufacture a crimped yarn by moistening an unstretched or partially stretched polyamide yarn with water, cold drawing, drying it in the untensioned state, and subjecting it to a heat treatment before or after the cold drawing but before the untensioned drying.

It was later shown that stretching synthetic yarns in such baths caused the formation of cracks or surface fillure. Starting from this observation, a process for the manufacture of slub yarns has been proposed in which the yarns are tensioned while in contact with an agent which causes crack or surface fillure, stretched to at least 1.01 times, and in general to approximately 2.5 times their initial length, withdrawn from the influence of the said agent and stretched to produce a slub yarn having an oriented structure.

It has also been proposed to manufacture textured yarns from a yarn whose structure has been rendered asymmetric during the spinning by the action of a cooling agent by tensioning it while it is in contact with a bath containing crack or surface fillure providing agent, moistening it with a liquid medium which is free from said agents and stretching it in the moistened state. Yarns of a cracked structure have also been manufactured by maturing in a cracking bath with gentle stretching and then withdrawing the yarns from the bath and stretching them strongly. However, apart from the fact that this process does not produce textured yarns but yarns having a ribbed surface, it requires several days to carry out.

All these methods either produce a product such as a slub yarn which cannot pretend to replace a textured yarn, or pro vide a textured yarn but using, at some stage, another conventional process for obtaining a textured yarn such as asymmetric cooling of the yarn during spinning, which is an operation ters of the fine and thick zones respectively and also of intermediate crystallinity and molecular orientation, the filaments furthermore possessing transverse grooves of attenuated relief at least in the thickest zones, and a nonspiral three-dimensional crimp and a high apparent volume.

While these textile articles can be made of any synthetic thermoplastic material, they are preferably made of a polyester e.g. polyethylene terephthalate.

In the case of polyethylene terephthalate the thick parts are unoriented and relatively crystalline, their crystallinity index being preferably less than 30 percent and their angle of molecular orientation 1) about Conversely, the thin parts are relatively crystalline and well oriented, having a crystallinity index which is preferably above 20 percent and advantageously between 30 and 60 percent and an angle of molecular orientation which is less than 40".

Unlike textured polyethylene terephthalate yarns obtained by stretching in a single stage and subsequent heat treatment in the relaxed state, the yarns of the invention show crystal-- lization and molecular orientation phenomena which are irreversible in character, as is shown by the breakage of the yarn during additional stretching. The new yarns also have good dyeing afiinity.

The overall crystallinity index value is determined by the method of W. O. Statton [Journal of Applied Polymer Science, vol. 7, pages 803-( l963)], the values for the angle of orientation by the method of W. A. Sisson [Journal of Textile Research, vol. 7, page 425-(l937)]. The values of the crystallinity indices and of the angles of orientation for the various zones are determined, taking into account the crystallinity indices and overall orientation of the yarn, the proportions by volume of the various zones, the appearance of the X- ray crystallograms, comparisons of fluorescence after dyeing of the various zones of one and the same yarn or of several yarns, and the morphology of these zones.

The invention also consists in a process for the manufacture of a textured continuous multifilament yarn of a synthetic thermoplastic material such as a polyester, by partial stretching of such a yarn in at least two stages, of which at least one is carried out while it is in contact with a crack or fillure promoting agent, followed by a heat treatment in the relaxed state.

Preferably the degree of stretching in the first stage is greater than that in the second. In the case of polyethylene terephthalate and for filament deniers below 12, the degree of stretching in the first stage is advantageously between 2 and 3, that of the second stage then advantageously being betwee L1 and 2.

The second stretching stage can be a cold stretching or a hot stretching. The crack or fillure promoting agent can of any known type, such as an alcohol, a glycol, dimethylformamide, kerosene, perchlorethylene, a polyoxyethylenic liquid of the Carbowax type, or pyridine. Such compounds are described in the literature. Preferably relatively cheap agents such as the lower alcohols are employed.

The heat treatment in the relaxed state can be carried out continuously with the stretching, or as an independent operation on the yarn or on a fabric, e.g. a woven fabric made therefrom, and may for example be combined with a dyeing treatment or a postsetting treatment of the woven fabric. This treatment can be carried out in one or more stages. The agent used may for example be steam, hot air, or a hot liquid bath.

The invention consists also in a device for carrying out the above process, comprising in sequence yam-feeding means, means for stretching the yarn in a bath containing crack or surface fillure promoting agent, means of stretching the yarn outside said bath, and winding-up means. It can moreover also comprise a heating means, such as a plate, heating box or the like, adapted to heat the yarn for the second stretching.

The device can also comprise means for the continuous heat treatment of the yarn in the relaxed state and/or dyeing means.

The invention will be'further described by reference to the accompanying drawing, in which:

FIG. 1 is a schematic view of a generalized device for carryingout the invention; and

FIG. 2 is a schematic representation of a yarn of the invention.

Referring now to FIG. 1, a bobbin 2 mounted on a creel 1 supplied a yarn 3 which is drawn off by feed rollers 4 and 5, after passing through a wire loop 6.

The yarn 3 is brought into contact with a crack or fillure promoting agent in a vat 7 and is stretched for the first time between the system of feed rollers 4 and 5 and a first set of stretching rollers 8 and 9 adapted to run at a higher peripheral speed than the feed rollers.

The yarn is thereafter stretched a second time between this first set of stretching rollers 8 and 9 and a second set of stretching rollers 10, 11 adapted to run at a yet higher peripheral speed. The yarn subsequently passes through a wire loop 12 and is collected by the wind-up system consisting of a spindle 15 with ring and cursor.

In one variant of the device a heating plate 13 is arranged between the bath 7 and the first set of stretching rollers 8, 9.

In another variant, the yarn 3 passes through a heating box 14 situated downstream from the second set of stretching rollers 10, 11 and upstream from a set of relaxing rollers 16 and 17 adapted to run at a lower peripheral speed than the rollers 10, 11.

In the following examples, which further illustrate the invention, the polyethylene terephthalate used has an intrinsic viscosity in o-chlorophenol of the usual value for textile yarns of this material, namely about 0.65.

. EXAMPLE I A 30filament polyethylene terephthalate yarn of filament denier 17.5 is treated on the above device (without the element for heat treatment in the relaxed state) using as crack or fillure promoting agent in the bath 25 percent aqueous ethanolat a temperature of 35 C.

The yarn is subsequently heat treated in the relaxed state in the following manner. It is dipped into water at 40 C., and the temperature of this water is then gradually raised to 100 C. and the yarn is kept at this temperature for 5 minutes. The yarn is thereafter dried under tension with free access of air, and is then treated in an oven at 180C. for 5 minutes.

The table which follows summarizes the properties of the yarn obtained with various degrees of stretching.

Degree of first stretch 2. 1 2. 1 2.1 2. 5 2. 8 Degree ofsecond stretch 1. 2 1. 7 1. S) 1.2 1. 2 Denier 250 1 180 220 200 Shrinkage in boiling water percent as 20 20 25 23 Crimp efiect. percent 2. 2 2. 1 1.7 1.7 2 Bulk cmfig'grams. 2. 1. f 1. 5 2. 3 2. 1 Elongation, percent 30 68 55 21 2. 1

The bulk is as determined by the Koningh test.

The crimp effect is determined by measuring a length 1 of the yarn under a load of 0.05 g.p.d., and then leaving the yarn for 24 hours under a load of 0.001 g.p.d., and measuring the new length 1,. The crimp effect is given by the ratio The shrinkage in boiling water is determined in the following manner: a length L (measured under a load of 0.05 g.p.d.) of the yarn is dipped into boiling water for two minutes, dried in an oven of 100 C. for 30 minutes, and suspended and left for minutes; the load of 0.05 g.p.d. is then reapplied, and the new length L, of the yarn is measured, the shrinkage in boiling water being expressed by the formula EXAMPLE 2 This is identical to the preceding example, except that a heating guide block at 120 C. is provided between the vat 7 and the first set of stretching rollers 8--9. The stretching data and the properties of the yarn obtained are as follows:

EXAMPLE 3 A 30 filament polyethylene terephthalate yarn of filament denier I8 is stretched first by a factor 0f2.1 in a vat containing 25 percent aqueous ethanol at 40 C., and continuously therewith is given a second stretch by a factor of 1.2 and is then heat-treated in the relaxed state in a stream box at 115 C.

The yarn obtained has the following characteristics:

Crimp effect percent 2.25

Bulk cm. /g 2.5

Strength g/denier 2.5

Shrinkage boiling water in percent 28 Elongation at break percent 30 This yarn has the appearance indicated schematically in FIG. 2 of the drawing, the diameter a of the fine parts being of the order of 30;/., the diameter b of the intermediate parts being approximately 36p. and the diameter c of the thick parts being about 50p.

The grooves are particularly well marked on the thick parts but it should be noted that their shape is very clearly attenuated compared to that observed on stretched yarns which have not been heat-treated in the relaxed state.

The orientation of the thin parts is good, the angle of orientation being 30, whilst the thick parts are completely unoriented, the angle p being about The intermediate parts have a rather low orientation, the angle of molecular orientation being between 30 and 90.

The yarn is noteworthy for its crimp which gives it the properties of textured yarns, its dimensional stability and its dyeing affinity.

This dyeing affinity can be demonstrated by the following experiment:

A woven fabric produced from the yarns obtained according to Example 3 and also from standard polyethylene terephthalate yarns of the same denier was dyed with a dyestuff consisting of a mixture of the following by weight:

0.3 percent ofDisperse Orange 11 (CI. 60,700)

0.6 percent ofDisperse Violet 1 (CI. 61,100)

3.5 percent ofDisperse Blue 7 (CI. 62,500)

(These dyestuffs are designated by their name given in the Color Index).

The bath furthermore contains 1 cm./litre of oxethylated castor oil as a dispersing agent and 1 cmP/litre of acetic acid. The dyeing is carried out in a vat with immersion at 40 C., and a progressive increase in temperature at the rate of 1 degree per minute up to 98 C., at which temperature the bath is kept for 90 minutes, followed by cooling and rinsing.

The yarn of the invention assumes the color perfectly whilst the standard yarn is hardly stained.

The yarns of the invention may be used by themselves or in mixtures, in the form of yarns of continuous lengths or of cut fibers, in the majority of textile applications, and can in particular be converted into woven or knitted fabrics.

Iclaim:

1. Continuous multifilament yarns of a synthetic thermoplastic material in which each filament comprises at least three types of zones of different mean diameter, the finest zones having the highest crystallinity and the greatest molecular orientation, the thickest zones having the lowest crystallinity and the least molecular orientation, and the intermediate zones being of a diameter between the extreme diameters of the finest and thickest zones and'having a crystallinity and molecular orientation between those of the finest and thickest zones, the filaments furthermore possessing transverse grooves of attenuated relief at least in the thickest zones, having a nonspiral three-dimensional crimp and a high apparent volume.

30 percent, and an angle of molecular orientation of about 5. Yarns according to claim 1, in which the thickest parts of the filaments are unoriented and relatively noncrystalline.

6. Yarns'according to claim 1, in which the thinnest parts of the filament are relatively crystalline and well oriented.

7. Staple fibers obtained from a yarn as defined in claim 1. 

